Drill stops have long been used to control the depth of a hole being drilled. The most common devices require the use of a tool to lock the drill stop on a drill such as an Allen wrench for tightening a set screw or a wrench for tightening nuts used to wedge a ferrule onto the drill. U.S. Pat. No. 3,620,637 apparently does not require separate tools for locking. In that patent, a collet having resilient fingers at each end is wedged onto the drill with a pair of overriding members threaded together.